Mummies made by the Chinchorro culture in Chile and Peru have survived for more than 7000 years. So when several of them suddenly started to turn into black ooze (pictured), scientists at the University of Tarapacá’s archaeological museum in Arica, Chile, knew right away that something was wrong. To figure out how to stop the degradation, they first needed to know what was causing it. The museum sent samples of damaged and undamaged mummy skin to Harvard University, where researchers cultured the microorganisms growing on each kind. They then transferred the cultures to pig skin and ran a series of tests to determine the conditions under which the microbes started munching away. It turns out that the mummies’ microbes kicked into high gear in high humidity—something the Chinchorro didn’t have to worry about living in and around the extremely arid Atacama Desert. In recent years, however, Arica has become increasingly more humid, possibly due to global climate change. Luckily for the museum’s mummies, more stringently controlling the humidity inside the collection is a relatively easy fix. But the changing climate in northern Chile may damage the hundreds of mummies that are likely still buried in shallow graves around Arica, with no protection from a changing climate. Soon, the researchers warn, archaeologists in search of the Chinchorro dead may find themselves digging up little more than sticky goop.